NEW YORK — The movie "300" rocks — and not just because Nine Inch Nails' "Just Like You Imagined" is used in a pivotal battle scene.

Actually, when you think about it, Nine Inch Nails has no place in a movie that takes place in 480 B.C., especially a movie that's not trying to be retro-postmodern, à la "A Knight's Tale" or "Marie Antoinette." But "300," due in March, is something else entirely: a fever dream that doesn't follow history to a T but tries to capture the essence of what it would be like to be a soldier or a king in ancient Greece — if that ancient Greece had been influenced by Southeast Asian fighting methods.

"It's not complying with the rules," director Zack Snyder said during an advance screening of portions of the film on Monday. "There's a couple movies that I ripped off a little bit — 'Excalibur,' 'Spartacus,' 'Gremlins' — but it's not my dad's swords-and-sandals movie, that's for sure."

Since "300" borrows from Frank Miller's graphic novel by the same name as much as the legendary comic writer borrowed from Herodotus' "Histories" and the 1962 movie "The 300 Spartans" (see "Frank Miller Says Bloody '300' Story Shaped His Whole Career"), there's a lot of wiggle room for interpretation about the Spartans' stand against the Persians, a classic last-stand tale that began when an emissary came from the Persian king and demanded the city-state's surrender.

"So they go meet up at a big table and decide not to fight," Snyder said. "Just kidding. Sparta was a warrior society. They didn't have a job other than that. Work out, eat, kill." But because of political reasons, the king isn't allowed to go to war, so he takes his own personal bodyguards — the 300 — to ward off the hundreds of thousands, if not millions, of soldiers from the invading army, even if it means suicide. This battle of Thermopylae helps unify Greece and give birth to Western Civilization (no small feat).

"I say millions of Persians," Snyder said, "because I'm the storyteller. That's my prerogative. I get to exaggerate. And from the standpoint of the storyteller, this is told through the prism of an ancient mind, so that's the aesthetic."

"These are oral histories," Miller said. "So over time, they're exaggerated, made up. If you really had these soldiers, these hoplites, with 75 pounds of shields and weaponry each, and the soldiers weighing 150 pounds themselves, then all you'd see is a little carpet of beetles running across the desert."

That wouldn't be very exciting, so Snyder takes certain liberties with his depiction of the Spartans and their foes — who include troll-like giants and elephant-like rhinos. Think "Gladiator" meets "Lord of the Rings" meets "Sin City," because the look of the scenes is as close to the original graphic novel as a film can get, only in this case, even better (a very rare feat). "If you look at the graphic novel, when you look at the frames, you see the 'why' of it," Snyder said. "It's the reason to make it into a movie. You always have to have a reason. Maybe you saw 'Milo & Otis,' and you say, 'I want to do a journey film.' But for me, when I look at King Leonidas drawing his sword, and the wolf and the boy, and the armies tumbling over the cliff, that's the reason, and it's a place to start."

"The key images are used, but man, I never used slow-mo like that," Miller said. "What an actor does with his lines, I can't do that."

The slow-mo comes into play for crucial fight moments, where much of the action stays at the same rate, but a key figure — usually King Leonidas (Gerard Butler) — is pulled into sharp focus as he slashes his way through several men while his contingent tries to keep up with the body count (see "Most Badass Epic Battle Now On Film In Frank Miller's '300' "). "I mentioned this is a family film, right?" Snyder laughed.

Snyder said he had the option of making the film more exact — not just as far as the story goes, but also in how he depicted this largely virtual world, mostly shot on green and blue screens. He could have matched up the action with a 3-D model on the computer in real time by attaching GPS to the camera. "Yeah, if I see that, I'm going to shoot somebody," he said. "Shoot it for real? That's crazy. I ended up cheating it anyway, and plus I saved millions of dollars. The rule was, if you can touch it, you build it. If it's any distance, then we didn't build it," he said.

"Everything was done inside," Snyder added, "except part of the horse battle, since we couldn't get the horses to ride over the hill fast enough inside."

"It made the fights easier, to do them in a more controlled environment," Butler said. "It was only harder for the dramatic scenes, where I was playing to something that didn't exist and talking about something that didn't exist. Especially the terrain — where the cliffs were, where the water was, looking at a burning village that's not a village and not burning. At the end of the day, it's rubber and cardboard. I spent a lot of time talking to nobody about nothing."

Except when he was screaming, his predominant mode of communication as seen in the trailer ("Tonight we dine in hell!"). "Run at each other and we'll see how quiet you are!" Miller laughed.

"I assure you that I don't just scream throughout the film," Butler laughed. "I've lost my voice filming other movies, but not in this one."